File Extension Database

Open OST File

OST files are data files, usual for the Microsoft Outlook program, in its online version.

In other words, all email services that work online, such as most IMAP account types, Microsoft 365 accounts, Exchange accounts, and Outlook.com accounts use the offline Outlook data file, or OST, to store a synchronized copy of the mailbox information on the local computer.

OST file, takes effect, when the connection to the mail server is interrupted. For example, when you are on a plane without WiFi or if the Internet connection is disconnected, with OST file you can still access all emails, calendar data, Contacts and tasks that have been previously downloaded.

Through the OST file, you can read and compose messages, create appointments, and add contacts.

However, it is necessary to be clear that e-mail messages will not be sent and new messages will not be downloaded until the Internet connection is reestablished.

When the connection is restored, the changes made to the OST file are automatically synchronized and the folders and items on the server and on the computer are identical again.

Software to open and work with an OST file

Microsoft Outlook

Frequently associated Windows objects:

OSTFile
Outlook.File.ost.14

How Can I Open OST File on Windows

We researched and learned that the best way to open OST file is to find a OST file in question in Windows OS File Explorer and double click on it to launch the corresponding application.
If a OST file is not opened in an application and you instead get a "Windows can't open a file" error message you should try looking for an application which can open the file in question.
If you know the application which can open OST file then run it and see if there is a File->Open main menu option in the application.
If you don't know the application which function as OST file opener then try to search online for "OST viewer", "application to open OST file" or "open OST file" queries in the search engine you like.
Install the application you found and check if it can open OST file

How Can I Open OST File on Mac OS

We recommend to find a OST file in question in Mac OS Finder and double click on it to launch the corresponding application.
If a OST file is not opened in a Mac OS application and you instead get a "There is no application set to open the file" error message you can click on "Search App Store" in the error dialog and Mac OS will show you applications compatible with OST file.
If you know the Mac OS application which can work as OST file opener you can choose the "Choose Application..." option in the error box to associate the file extension and open OST file in it.
If you don't know the application which can open OST file then try to search for "OST viewer", "application to open OST file" or "read OST file" queries in the online search engine you like.
Install the application you found and check if it can read OST file

How Can I Open OST File on Android

If you downloaded a OST file on Android device you can open it by following steps below:

In the Android apps list on your Android device find "My Files" or "File manager" app and tap to start it.
Tap on "Downloads" folder inside the app.
You should see your downloaded OST file in that folder.
Tap on the file. If Android device supports opening the file you downloaded it will open in the corresponding app.
If file does not open you can look for the corresponding app that can open the file by searching Android App Store for the "OST".
If you cannot open the file with the apps from Android App Store it is possible that the file could only be opened on desktop platforms such as Windows or Mac OS. Try searching for "OST viewer", "OST file reader" online and see if any desktop applications can open it.
It is also possible that the file you downloaded is outdated and is no longer supported.

How to Open OST File on iPhone or iPad

To open OST File on iOS device follow steps below:

We advies to open Files app on your iPhone or iPad device. You can find it by swiping down on the home screen and typing "Files" in the search bar.
Tap on the Downloads folder on the Files app home screen.
You will see all files that you recently downloaded. Tap on the OST file to view it.
If you have the right app that can open it it will automatically launch and open your file.
If you don't have the app which can open it you need to serch Apple app store for "OST". This way you can find apps which can open OST files.
If this doesn't help it is possible that your file could be opened only by the desktop application. To find an app which can open it on desktop look for "OST viewer" or "OST file" online in your favorite search engine.

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